From the "JPL Universe"
February 25, 1994


LAB PLAYING KEY ROLE IN CLEMENTINE MISSION TO MAP MOON, FLY BY ASTEROID

By Mark Whalen


JPL is playing an important role in a joint
military-scientific mission that will space-qualify lightweight
sensors and component technologies for the next generation of
Defense Department spacecraft, map the Moon, and conclude with a
close encounter with a near-Earth asteroid.
The Clementine mission, sponsored by the Ballistic Missile
Defense Organization (BMDO) (formerly known as the Strategic
Defense Initiative Organization) was launched Jan. 25 from
Vandenberg Air Force Base on a Titan II-G rocket; the
231-kilogram (508-pound) spacecraft went into a polar lunar orbit
Feb. 19. Systematic lunar mapping is scheduled to begin about a
week later and continue through early May, followed by the first
flyby of the near-Earth asteroid 1620 Geographos. The $75-million
mission took only 22 months from conception to launch.
Designed and built by the Naval Research Laboratory (NRL),
the spacecraft was originally conceived to test advanced,
lightweight technologies for ballistic-missile defense
applications. Lawrence Livermore National Laboratory of
California built most of the scientific payload. NASA became
involved when scientists arranged to participate in the mission
to create unprecedented maps of the moon in addition to the
asteroid encounter.
The Lab is supporting the mission on four fronts, with teams
overseeing a radiation and reliability experiment for advanced
microelectronic devices; dynamical, photometric and cartographic
studies; Deep Space Network (DSN) tracking and navigation; and
engineering studies of the Clementine systems' performance and
Clementine's daughter satellite, the Interstage Adapter Satellite
(ISAS).
Dr. Satish Khanna of the Center for Space Microelectronics
Technology Division 820 is program manager for RRELAX (the
Radiation and Reliability Assurance Experiment), which will
characterize the radiation resistance and reliability of three
advanced microelectronic devices: charged-couple devices,
complementary metal oxide silicon and static random-access
memory. The experiment, whose principal investigator is Dr.
Martin Buehler of Section 346, comprises two hardware boxes, one
on the spacecraft and one on the ISAS.
Khanna said that "within nine months, we designed,
fabricated, tested and delivered the two RRELAX boxes to NRL for
integration into the spacecraft and ISAS.
"This experience will be useful for JPL's plan to
participate in cheaper, faster and better missions," he added.
Tom Duxbury of the Geology and Planetology Section 326 is
one of the three JPL members of the NASA-sponsored science team.
"We will obtain high-resolution coverage of the moon," he said,
"with precision radio science yielding the gravity field, a laser
altimeter giving topography, and stereo imaging giving a global
cartographic control network--the first time we have had those
simultaneously."
The total amount of data transmitted from the moon mapping
will be comparable to that obtained during the first Magellan
mapping cycle of Venus. "It's global coverage, not just bits and
pieces or strips (of the moon)," Duxbury added. Earlier missions
to the moon, including Apollo, mainly orbited the equatorial
regions.
Clementine is scheduled to reach Geographos on Aug. 31,
after which time more than 2,000 images will be recorded and
stored on board in the solid-state memory for later playback to
Earth. Duxbury said the cigar-shaped asteroid measures about 1
1/2 km by 4 km (9/10 mile by 2 1/2 miles), and its orbit is
inclined about 16 degrees to Earth's ecliptic plane. The
spacecraft will pass within 100 km (62 miles) of Geographos, when
it will be 8 million km (5 million miles) from Earth.
Clementine's cameras will be programmed to autonomously
track the asteroid while passing from the dark to the sunlit side
at close range; as the spacecraft goes by, most of the
illuminated side will come into view. (A three-member optical
navigation team from JPL's Section 314 will support this part of
the mission.) Close-range images, when combined with Light
Detection and Ranging (LIDAR) measurements, will enable an
accurate determination of the asteroid's shape and size.
JPL tracking stations at Goldstone, Calif.; Madrid, Spain;
and Canberra, Australia--in conjunction with an NRL station in
Pomonkey, Md., and a number of Air Force stations--will support
the Clementine mission, according to Ray Amorose, manager of the
TDA Mission Support and DSN Operations Division 440.
"In general," he said, "we are using our 26-meter subnet,
with some 34-meter support; in late May, it will be all 34-meter
coverage because the spacecraft will be out of range of the
26-meter antennas. When the spacecraft gets to the asteroid,
there will be a couple of days of 70-meter coverage.
"We're doing navigation and orbit-determination work,"
Amorose added. "Goddard Space Flight Center in Maryland is
assisting NRL in orbit-determination and dynamics work on the
early part of the mission; when it leaves the moon, then JPL
becomes a major player for the navigation."
About 30 JPL staff members are working on the mission.
Amorose noted that a particularly special effort has been made in
recent weeks by Al Berman of Division 440, the project's tracking
and data system manager, whose Granada Hills home was severely
damaged by the Jan. 17 Northridge earthquake. "He came in anyway
and did his job," Amorose said. "He is a pretty dedicated guy."
In addition to the on-Lab support, Dr. Henry Garrett of
Division 52 is currently on detail to the Clementine program
office. Garrett heads the Clementine engineering team, which is
evaluating the overall performance of the advanced technologies
being tested on the vehicle. He is also program manager for ISAS,
which was left behind by the main Clementine spacecraft following
the first lunar transfer orbit injection.
The ISAS carries a copy of the RRELAX experiment, a dust
detector provided by NASA's Langley Research Center, and several microelectronics experiments provided by NRL. The NRL-designed
package cost less than $1 million and is intended to serve as a
test of Clementine's microelectronics in the Earth's radiation
environment, Garrett said. JPL is currently receiving data on the
radiation environment and on the performance of the RRELAX test
devices from both the ISAS and Clementine.
The Clementine mission is the first non-NASA deep-space
mission conducted by the United States. "As far as the NASA
science community is concerned, it's a high-payoff mission,"
Duxbury said. "For the Defense Department, it's testing specific
technology it needs to do its business."
According to a BMDO statement, "The use of celestial bodies
such as the moon and a near-Earth asteroid makes ideal targets to flight-qualify advanced lightweight technologies developed by
BMDO. The added cost of the mission by going to deep space is
actually less than the cost of developing and deploying the
targets that would be required to test the payload in low-Earth
orbit.
"By performing a joint mission with NASA and forming a
NASA-selected science team to enhance the scientific value of the
mission, it will also be possible to transfer these technologies
for future space exploration."

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___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ Galileo S-Band | A mind stretched by a new /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | idea can never go back to |_____|/ |_|/ |_____|/ | its original dimensions.



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